Hyaluronic acid is a mucoid polysaccharide of biological origin. The sodium salt, sodium hyaluronate, in buffered physiological saline solution, has found significant use as a vitreous replacement in optical surgery and in other medical applications. Some of these applications are described in U.S. Pat. Nos. 4,141,973 and 4,328,803. For such medical purposes, a pyrogen-free, highly purified sodium hyaluronate having a molecular weight in excess of 750,000 has heretofore been used. A commercial product known as HEALON.TM., manufactured by Pharmacia, Inc., Piscataway, N.J., is a one-percent solution of sodium hyaluronate sold for such purposes. For example, dilute HEALON.TM. solution (0.1-0.2% sodium hyaluronate) has been reported to be useful as an eye drop for the treatment of patients with keratitis sicca syndrome.
Hyaluronic acid has also been used as an ingredient for in vitro culture of leprosy baccili and as a component for cosmetic formulations. Cosmetic formulations, which are described in U.S. Pat. No. 4,303,676, include both a low molecular weight fraction (about 10-50,000) and a higher molecular weight fraction (in excess of 1.times.10.sup.6).
The source of hyaluronic acid for all of the foregoing uses have been rooster combs, human umbilical cords or other vertebrate tissue. Extraction and purification of hyaluronic acid from such tissue is a relatively complex process which results in a very expensive product.
Hyaluronic acid can be produced by Group A and C strains of Streptococcus bacteria. One use reported for the bacterial product appears to be as a reagent for determination of anti-streptococcal hyaluronidase in human serum samples, Kjems and Lebech, Acta Path. microbiol scand., Section B, 84: 162-164 (1976). In that paper, the authors describe a defined media for growing Group A streptococci and isolating hyaluronic acid, reporting a yield of 0.3 grams per liter of culture broth. However, hyaluronic acid produced by bacteria has not found substantial use because it is of a low molecular weight range.